Terrorism, insurgency and transnational crime remained persistent security threats in archipelagic Southeast Asia throughout 2016. While the threat of attacks and kidnappings by insurgent and hybrid terrorist-criminal groups is primarily centred on the Philippines, the existence of other capable and ideologically aligned groups, ungoverned spaces and weak state institutions in the Mindanao–Sulawesi–Sabah triangle and beyond presents a broader threat to regional security, and potentially to maritime trade. However, the increasing number of groups with connections of varying degrees to the self-styled Islamic State, also known as ISIS or ISIL, and the networked nature of the region’s armed groups, have catalysed a greater degree of security cooperation than has so far been the norm.

On 1 August 2016, Indonesia, Malaysia and the Philippines signed an agreement on coordin­ated joint patrols in the Sulu Sea – the Sulu Sea Trilateral Initiative. It was a direct response to piracy and kidnapping activities in the maritime region. Malaysian Defence Minister Hishammuddin Hussein explained the motivations for the agreement at the IISS Fullerton Forum in January 2017: ‘Militant groups in the area have internationalised their operations across boundaries, rejecting existing state identities and allegiances and duplicating [ISIS’s] modus operandi. A united multi-state front comprising a tri-nation military force will shatter any dreams of a utopian state caliphate establishing itself in the region.’